Despite significant reduction in the prevalence of dental caries in some segments of the population it remains a major public health problem, particularly for those least able to bear the burden. The decline in prevalence has generally been attributed to increased exposure to fluoride through a variety of routes. Prior to and during the increased use of fluorides ingestion with food preservatives was also increasing by over 25 fold. Food preservatives have properties in common with fluoride in that they behave as weak acids they are protonated at low pH values, can diffuse into cells, reduce acid tolerance and acid adaptation by mutants streptococci. Recognizing the importance of saliva on the plaque environment, we will examine the relationship of mammalian and non- mammalian components of whole saliva samples collected over a three- year period, to the incidence of dental caries in the same group of subjects. We believe this proposal is highly novel and offers the possibility of developing approaches to enhance the diagnosis of caries and methods for its prevention.